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2017 CAO CONGRESS POSTER ABSTRACTS

Characteristics of posterior corneal astigmatism in the different stages of keratoconus

Masoud Khorrami-Nejad, MS1;Fereshteh Aslani, MS1; Mohamad Amiri, OD1; Hesam Hashemian,
MD2; Farshad Asgarizadeh, MS3
1 - Department of Optometry, Faculty of Rehabilitation, Shahid Beheshti University of Medical Science
2 - Eye Research center, Farabi Eye Hospital, Tehran University of Medical Science, Tehran, Iran
3 - Refractive Errors Research Center, School of Paramedical Sciences, Mashhad University of Medical
Sciences, Mashhad, Iran

PURPOSE
To evaluate the magnitudes, axis orientation, ratio and correlation of anterior corneal astigmatism (ACA) and pos-
terior corneal astigmatism (PCA) in the different stages of keratoconus (KC).

METHODS
This retrospective case series study comprises 161 eyes of 161 KC patients (104 men and 57 women; mean age ± stan-
dard deviation,22.35± 6.10 years) that were divided into 4 subgroups according to the Amsler-Krumeich classification.
Scheimpflug imaging system (OCULUS Optikgerate GmbH, Wetzlar, Germany)was used to measure the magnitude
and the axis orientation of ACA and PCA. The posterior–anterior corneal astigmatism ratio was also calculated.

R E S U LT S
The average amounts of anterior, posterior, and total central corneal astigmatism were 4.08 ± 2.21 Diopters (D), 0.86
± 0.46 D, and 3.50 ± 1.94 D, respectively. With-the-rule (WTR), against-the-rule (ATR), and oblique astigmatism
of the posterior surface of corneal were found in 61 eyes (37.9%), 67 eyes (41.6%), and 33 eyes (20.5%). Respec-
tively, whereas the corresponding astigmatism of the anterior corneal surface was found in 55 eyes (32.4%), 56 eyes
(34.8%), and 50 eyes (31.1%), respectively. A strong correlation (P=0.001, r=0.839) was found between ACA and PCA
in the different stages of KC; the correlation was weaker in grades 3(P=0.001, r=0.711) and 4(P=0.001, r=0.717) KC
cases. The maximum amount of posterior–anterior corneal astigmatism ratio was in stage 1 of KC patients (0.246).

CONCLUSION
Cornea astigmatism in anterior surface was more affected than posterior surface by increasing in the KC severity,
although PCA was more affected than ACA in an early stage of KC.

Refractive outcomes after intracorneal ring implantation

Masoud Khorrami-Nejad, MS1;Mohsen Ghorbani, MS1; Mohamad Amiri, OD1; Mahsa Ranjbar
Pazooki, BS2; Hesam Hashemian, MD2; Farshad Asgarizadeh, MS3
1 - Department of Optometry, Faculty of Rehabilitation, Shahid Beheshti University of Medical Science
2 -Eye Research center, Farabi Eye Hospital, Tehran University of Medical Science, Tehran, Iran
3 -Refractive Errors Research Center, School of Paramedical Sciences, Mashhad University of
Medical Sciences, Mashhad, Iran

PURPOSE
The investigation of refractive error and visual acuity before and 6 months after myoring implantation in patients
with keratoconus at Farabi hospital in Tehran, Iran.

METHODS
In this retrospective study, thirty-four eyes of twenty-eight keratoconic patients files with mean age of 29 ± 7.41 un-
derwent myoring operation and they were reevaluated after 6 months. In these patients best corrected visual acuity
(BCVA), refractive outcomes and Pentacam [Oculus GmbH] findings were assessed. All patients had clear central
corneas, contact lens intolerance, and a central corneal thickness of more than 360 mm.

R E S U LT S
Six months postoperately, the mean BCVA (in LogMAR value) improved significantly from 0.30 ±0.22 to 0.20 ± 0.20
(p=0.006) and the mean spherical refractive error improved from -4.66 diopters(D) ± 3.76 to -1.48D ± 3.72 (p<0.001).
The mean cylindrical refractive error decreased significantly from -4.27D ±3.15 to -2.18D ±1.63 (P<0.001).

CANADIAN JOURNAL of OPTOMETRY | REVUE CANADIENNE D’OPTOMÉTRIE VOL. 79 NO. 2 33